Revealing the Size Effect of Ceria Nanocube-Supported Platinum Nanoparticles in Complete Propane Oxidation

The elimination of propane is one of the key tasks in reducing volatile organic compounds (VOCs) and automotive exhaust emissions. The platinum nanoparticle (NP) is a promising catalyst for propane oxidation, while the study of its structural characteristics and functionality remains in its infancy. In this work, we synthesized the nanocubes CeO₂ with a well-defined (100) facet supporting Pt NPs with various sizes, from 1.3 to 7 nm, and systematically investigated the effect of the Pt size on complete propane oxidation efficiency. In particular, CeO₂(100) supported Pt NPs smaller than 4 nm promote the formation of positively charged Pt sites, which hinder the adsorption and activation of propane and reduce the intrinsic activity for propane oxidation. Consequently, within this size range, the catalytic performance is primarily influenced by the electronic state of the Pt species, with metallic Pt being identified as the active site for the reaction. Conversely, as the particle size exceeds 4 nm, metallic Pt particles become dominant and the geometric structure starts to influence the activity as well. Such entanglement of electronic and geometric factors gives rise to a volcano relationship between reaction rates and Pt particle sizes ranging from 1.3 to 7 nm, while an increased correlation can be observed between the turnover frequencies and the particle sizes in this range. This knowledge can guide the synthesis of highly active catalysts, enabling the efficient oxidation of VOCs with reduced precious metal loadings.